In order to solve the problems, U.S. Pat. No. 5,707,347, which was registered in 1998, has been proposed. As shown in FIG. 1, the impact-dispersing knee brace of the cited document includes an upper cuff 1, a lower cuff 3, and a support 2. The upper cuff includes arcuate anterior and posterior segments 1a and 1b, which are fastened to the thigh region surrounding the thighbone of the leg, and a coupling band 1c which couples the anterior and posterior segments to each other. The lower cuff includes anterior and posterior segments 3a and 3b, which are fastened to the calf region surrounding the shinbone of the leg, and a coupling band 3c, which couples the anterior and posterior segments to each other. The support comprises a pair of arms between the upper cuff 1 and the lower cuff 3, and is operated in the manner of a hinge.
The hinge-operating support 2 is connected at both ends thereof to the upper cuff 1 and the lower cuff 3. A spring is provided at each of the connecting points to elastically bias the support 2, thus dispersing the impact of the knee joint to the upper cuff 1 and the lower cuff 3.
However, such a conventional impact-dispersing knee brace has a drawback in that it does not consider the anatomical shape of the human body and in that the hinge-operating support is provided between the upper cuff and the lower cuff, so that it is very inconvenient to bend or stretch the joint in response to the motion of the body. Further, the conventional impact-dispersing knee brace has no adjusting means for compensating for imbalance between the left and right sides of cartilage, so that it is impossible to relieve a patient's knee pain.
In order to solve the problems, Korean U.M. Registration No. 0378573 has been proposed, which was filed by the applicant of this invention and is entitled ‘Knee Protection and Impact Relief Device for Knee Protection Brace’.
According to U.M. Registration No. 0378573, the device includes a tubular body, an upper cuff, a lower cuff, a movable pin, a hinge, and a spring. The tubular body has on an upper portion thereof an upper opening. The tubular body has on a lower portion thereof a lower opening, so that supporting plates of the lower cuff are integrated with the body. A hole is formed in the central portion of the tubular body, and a semi-circular moving slot is formed at a position around the hole. The upper cuff has a ring, which is provided on the lower surface of the upper cuff, which is retractably inserted into the upper opening of the tubular body. The lower cuff has the plurality of integrated supporting plates. Each of the supporting plates has on an upper portion thereof a moving slot, and has a hole under the moving slot, so that the lower cuff is inserted into the lower opening of the tubular body. A rotary part is provided on the central portion of the lower cuff. The movable pin is movably inserted into the moving slot of the lower cuff and the moving slot of the tubular body, which are aligned with each other. The hinge is inserted into the hole of the lower cuff and the hole of the tubular body, which are aligned with each other. The spring is inserted into the tubular body. One end of the spring is coupled to the ring of the upper cuff, while the other end of the spring is coupled to the moving slot of the lower cuff.
According to U.M. Registration No. 0378573, in order to minimize friction and impact acting on the knee cartilage due to a user's body weight, the thighbone and the shinbone are pulled away from the cartilage so that a small load acts on the cartilage even when the foot contacts the ground. However, according to the bend angle of the knee, the elastic force of the spring varies. That is, as the elastic force is increased, the thighbone is efficiently pushed up. As a result, the user must bend his or her knee as much as possible when he or she walks, thus causing inconvenience.
Further, unless the lower cuff is firmly secured to the shinbone region (e.g.: the calf region), when the upper cuff secured to the thighbone region (e.g.: the inguinal region) is pushed up by the elastic force or the restoring force of the spring, the lower cuff is pushed down. Thus, the device may undesirably slide down from the knee. In order to overcome this problem, if the lower cuff is too firmly secured to the shinbone region, it hinders the blood circulation of the leg. Therefore, it is impossible to wear the device for a lengthy period of time.
In order to solve the problems, Korean Patent Appln. No. 10-2005-0032044 was proposed by the applicant of this invention. According to the cited document, a knee joint brace relieves pain and impact acting on the knee joint using a spring and a cam when the knee is extended.
According to Korean Patent Appln. No. 10-2005-0032044, an upper cuff secured to the thighbone region is shaped so that its upper portion is wide and its lower portion is narrow, and a lower cuff secured to the shinbone region is shaped so that its upper portion is narrow and its lower portion is wide, thus reliably tightening the upper and lower portions of the leg. The knee joint brace includes the upper cuff, which performs a vertical motion using a compression means that is pushed up by the rotating movement of the lower cuff, and a tubular body which engages with a cam shaft of the lower cuff, which is inserted into the open lower end of the tubular body, and accommodates the upper cuff, which is inserted into the open upper end of the tubular body.
However, according to Korean Patent Appln. No. 10-2005-0032044, one hinge or the cam shaft, such as a pivot point, is placed on the extrapolated line of the rotating motion of the knee. When the cam rotates about the cam shaft in the tubular body, a spring, coupled to a silicone plate, contracts, so that the upper cuff is pushed up.
However, the prior art disclosed in Korean Patent Appln. No. 10-2005-0032044 is problematic in that a large load acts on the cam and the rotation of the cam is not converted into a vertical stroke (linear moving distance for moving the upper cuff up) because of the shape and structure of the cam, so that the natural rotation of the knee is hindered and it is difficult to secure rigidity due to the shape of the cam.
Further, according to the prior art, when a flat silicone plate compresses the spring, slipping or unnatural operation may occur, and a lot of sliding noise is generated. Thus, it is difficult to perform a smooth shock absorbing action.
Further, when cartilage wears out due to specific diseases (e.g.: degenerative arthritis) or the diseases of old age, a joint cavity filled with synovial fluid malfunctions, excessive friction or direct collision occurs between the articular cartilage of the thighbone and the meniscus of the shinbone, or the left and right sides of the knee cartilage are imbalanced, the knee joint is deformed or pain is caused. The conventional knee brace or protector has a drawback in that smooth rotation and shock absorbing action cannot be realized while the balance between the left and right sides of the knee cartilage is adjusted.
In the conventional knee protectors, a part performing the shock absorbing action is limited to the tubular body or the shaft inserted into the tubular body, so that the width of the shock absorbing part is narrow. Thus, flexural deformation caused by vertical moving force and twisting force of the body acts on the narrow tubular body or shaft. Hence, the part which performs the shock absorbing action of the knee joint and the subsidiary function of joint movement cannot stably support the upper cuff and the lower cuff.
Further, the conventional knee protectors are problematic in that a spring, which has a relatively shorter stroke distance in consideration of the load acting on the leg, or has a lower allowance in consideration of maximum tolerance compression height, so that the knee is overstrained.
Further, the conventional knee protectors are problematic in that shock absorbing action occurs only in the tubular body and the shaft inserted into the tubular body, so that shocks cannot be smoothly absorbed and the tubular body may be broken. The conventional knee protectors cannot overcome the low fatigue resistance of the spring, which absorbs shocks for a lengthy period of time, so that it is difficult to generate sufficient shock absorbing force, and durability is very low.
According to the prior art, the shaft inserted into the tubular body is integrated with the upper cuff. Thus, when a specific portion of the upper cuff is broken, the entire upper cuff must be separated from the lower cuff and be replaced with a new one. As such, the conventional knee protectors have a structural problem, and are inconvenient to maintain.
Further, according to the prior art, an upper or lower tightening part using a coil spring is provided to firmly secure the upper or lower cuff to the body. However, it is very complicated and inconvenient to manufacture the tightening part. The tightening part cannot closely correspond to the anatomical shape of the human body.